1 /* 2 * Copyright 2014 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef GrFragmentProcessor_DEFINED 9 #define GrFragmentProcessor_DEFINED 10 11 #include "GrProcessor.h" 12 13 class GrCoordTransform; 14 class GrGLSLCaps; 15 class GrGLSLFragmentProcessor; 16 class GrInvariantOutput; 17 class GrProcessorKeyBuilder; 18 19 /** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and 20 produce an output color. They may reference textures and uniforms. They may use 21 GrCoordTransforms to receive a transformation of the local coordinates that map from local space 22 to the fragment being processed. 23 */ 24 class GrFragmentProcessor : public GrProcessor { 25 public: 26 /** 27 * In many instances (e.g. SkShader::asFragmentProcessor() implementations) it is desirable to 28 * only consider the input color's alpha. However, there is a competing desire to have reusable 29 * GrFragmentProcessor subclasses that can be used in other scenarios where the entire input 30 * color is considered. This function exists to filter the input color and pass it to a FP. It 31 * does so by returning a parent FP that multiplies the passed in FPs output by the parent's 32 * input alpha. The passed in FP will not receive an input color. 33 */ 34 static const GrFragmentProcessor* MulOutputByInputAlpha(const GrFragmentProcessor*); 35 36 /** 37 * Similar to the above but it modulates the output r,g,b of the child processor by the input 38 * rgb and then multiplies all the components by the input alpha. This effectively modulates 39 * the child processor's premul color by a unpremul'ed input and produces a premul output 40 */ 41 static const GrFragmentProcessor* MulOutputByInputUnpremulColor(const GrFragmentProcessor*); 42 43 /** 44 * Returns a parent fragment processor that adopts the passed fragment processor as a child. 45 * The parent will ignore its input color and instead feed the passed in color as input to the 46 * child. 47 */ 48 static const GrFragmentProcessor* OverrideInput(const GrFragmentProcessor*, GrColor); 49 50 /** 51 * Returns a fragment processor that runs the passed in array of fragment processors in a 52 * series. The original input is passed to the first, the first's output is passed to the 53 * second, etc. The output of the returned processor is the output of the last processor of the 54 * series. 55 */ 56 static const GrFragmentProcessor* RunInSeries(const GrFragmentProcessor*[], int cnt); 57 58 GrFragmentProcessor() 59 : INHERITED() 60 , fUsesLocalCoords(false) 61 , fNumTexturesExclChildren(0) 62 , fNumTransformsExclChildren(0) {} 63 64 ~GrFragmentProcessor() override; 65 66 GrGLSLFragmentProcessor* createGLSLInstance() const; 67 68 void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const { 69 this->onGetGLSLProcessorKey(caps, b); 70 for (int i = 0; i < fChildProcessors.count(); ++i) { 71 fChildProcessors[i]->getGLSLProcessorKey(caps, b); 72 } 73 } 74 75 int numTexturesExclChildren() const { return fNumTexturesExclChildren; } 76 77 int numTransformsExclChildren() const { return fNumTransformsExclChildren; } 78 79 int numTransforms() const { return fCoordTransforms.count(); } 80 81 /** Returns the coordinate transformation at index. index must be valid according to 82 numTransforms(). */ 83 const GrCoordTransform& coordTransform(int index) const { return *fCoordTransforms[index]; } 84 85 const SkTArray<const GrCoordTransform*, true>& coordTransforms() const { 86 return fCoordTransforms; 87 } 88 89 void gatherCoordTransforms(SkTArray<const GrCoordTransform*, true>* outTransforms) const { 90 if (!fCoordTransforms.empty()) { 91 outTransforms->push_back_n(fCoordTransforms.count(), fCoordTransforms.begin()); 92 } 93 } 94 95 int numChildProcessors() const { return fChildProcessors.count(); } 96 97 const GrFragmentProcessor& childProcessor(int index) const { return *fChildProcessors[index]; } 98 99 /** Do any of the coordtransforms for this processor require local coords? */ 100 bool usesLocalCoords() const { return fUsesLocalCoords; } 101 102 /** Returns true if this and other processor conservatively draw identically. It can only return 103 true when the two processor are of the same subclass (i.e. they return the same object from 104 from getFactory()). 105 106 A return value of true from isEqual() should not be used to test whether the processor would 107 generate the same shader code. To test for identical code generation use getGLSLProcessorKey 108 */ 109 bool isEqual(const GrFragmentProcessor& that, bool ignoreCoordTransforms) const; 110 111 /** 112 * This function is used to perform optimizations. When called the invarientOuput param 113 * indicate whether the input components to this processor in the FS will have known values. 114 * In inout the validFlags member is a bitfield of GrColorComponentFlags. The isSingleComponent 115 * member indicates whether the input will be 1 or 4 bytes. The function updates the members of 116 * inout to indicate known values of its output. A component of the color member only has 117 * meaning if the corresponding bit in validFlags is set. 118 */ 119 void computeInvariantOutput(GrInvariantOutput* inout) const { 120 this->onComputeInvariantOutput(inout); 121 } 122 123 protected: 124 void addTextureAccess(const GrTextureAccess* textureAccess) override; 125 126 /** 127 * Fragment Processor subclasses call this from their constructor to register coordinate 128 * transformations. Coord transforms provide a mechanism for a processor to receive coordinates 129 * in their FS code. The matrix expresses a transformation from local space. For a given 130 * fragment the matrix will be applied to the local coordinate that maps to the fragment. 131 * 132 * When the transformation has perspective, the transformed coordinates will have 133 * 3 components. Otherwise they'll have 2. 134 * 135 * This must only be called from the constructor because GrProcessors are immutable. The 136 * processor subclass manages the lifetime of the transformations (this function only stores a 137 * pointer). The GrCoordTransform is typically a member field of the GrProcessor subclass. 138 * 139 * A processor subclass that has multiple methods of construction should always add its coord 140 * transforms in a consistent order. The non-virtual implementation of isEqual() automatically 141 * compares transforms and will assume they line up across the two processor instances. 142 */ 143 void addCoordTransform(const GrCoordTransform*); 144 145 /** 146 * FragmentProcessor subclasses call this from their constructor to register any child 147 * FragmentProcessors they have. This must be called AFTER all texture accesses and coord 148 * transforms have been added. 149 * This is for processors whose shader code will be composed of nested processors whose output 150 * colors will be combined somehow to produce its output color. Registering these child 151 * processors will allow the ProgramBuilder to automatically handle their transformed coords and 152 * texture accesses and mangle their uniform and output color names. 153 */ 154 int registerChildProcessor(const GrFragmentProcessor* child); 155 156 /** 157 * Subclass implements this to support getConstantColorComponents(...). 158 * 159 * Note: it's up to the subclass implementation to do any recursive call to compute the child 160 * procs' output invariants; computeInvariantOutput will not be recursive. 161 */ 162 virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0; 163 164 private: 165 void notifyRefCntIsZero() const final; 166 167 /** Returns a new instance of the appropriate *GL* implementation class 168 for the given GrFragmentProcessor; caller is responsible for deleting 169 the object. */ 170 virtual GrGLSLFragmentProcessor* onCreateGLSLInstance() const = 0; 171 172 /** Implemented using GLFragmentProcessor::GenKey as described in this class's comment. */ 173 virtual void onGetGLSLProcessorKey(const GrGLSLCaps& caps, 174 GrProcessorKeyBuilder* b) const = 0; 175 176 /** 177 * Subclass implements this to support isEqual(). It will only be called if it is known that 178 * the two processors are of the same subclass (i.e. they return the same object from 179 * getFactory()). The processor subclass should not compare its coord transforms as that will 180 * be performed automatically in the non-virtual isEqual(). 181 */ 182 virtual bool onIsEqual(const GrFragmentProcessor&) const = 0; 183 184 bool hasSameTransforms(const GrFragmentProcessor&) const; 185 186 bool fUsesLocalCoords; 187 188 /** 189 * fCoordTransforms stores the transforms of this proc, followed by all the transforms of this 190 * proc's children. In other words, each proc stores all the transforms of its subtree as if 191 * they were collected using preorder traversal. 192 * 193 * Example: 194 * Suppose we have frag proc A, who has two children B and D. B has a child C, and D has 195 * two children E and F. Suppose procs A, B, C, D, E, F have 1, 2, 1, 1, 3, 2 transforms 196 * respectively. The following shows what the fCoordTransforms array of each proc would contain: 197 * 198 * (A) 199 * [a1,b1,b2,c1,d1,e1,e2,e3,f1,f2] 200 * / \ 201 * / \ 202 * (B) (D) 203 * [b1,b2,c1] [d1,e1,e2,e3,f1,f2] 204 * / / \ 205 * / / \ 206 * (C) (E) (F) 207 * [c1] [e1,e2,e3] [f1,f2] 208 * 209 * The same goes for fTextureAccesses with textures. 210 */ 211 SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms; 212 int fNumTexturesExclChildren; 213 int fNumTransformsExclChildren; 214 SkSTArray<1, const GrFragmentProcessor*, true> fChildProcessors; 215 216 typedef GrProcessor INHERITED; 217 }; 218 219 #endif 220
